This invention relates to a piston for pressure fluid operated cylinders.
In my U.S. Pat. No. 3,605,553 a piston for pressure fluid operated cylinders has been disclosed, comprising fixed on the piston rod a disc member having a diameter substantially smaller than the inner diameter of the cylinder chamber and a sleeve-like member of elastic material projecting peripherally and laterally with respect to both sides of said disc member connected therewith. Said sleeve-like member engages at the end portions thereof the cylinder chamber, a reduced diameter intermediate zone being provided in said sleeve like-member, the respective end portions of the sleeve-like member penetrating alternatively, at the end of stroke positions in a respective annular seat forming therewith a damping chamber.
In the practical use of the above described piston it has been observed that, owing to the fact that the piston had to be forced into the cylinder chamber in order to obtain the required sealing, at the start of operation, after a resting period, a rather relevant starting friction developed between the piston and the cylinder chamber, with the consequent irregularity in the operation and difficulties during the starting stage.